The invention relates to a method of manufacturing a multi-core ferrule, which is particularly strict in dimensional accuracy among ferrules, which are main components of connectors for use in connection of optical fibers or of devices.
There are demands for such types of multi-core ferrules for use in optical connectors, devices or the like that have cores or apertures of from about 2, 4, 6, 8, 10, 12 up to about 100 or more in desired positions.
However, practical multi-core ferrules now commercially available are no more than two-core type zirconia ferrules, and the actuality is that it is substantially impossible to manufacture those having more than two cores due the difficulty in achieving extremely strict accuracy on the order of microns in terms of the bore diameter and the position of the apertures.
To explain the above-mentioned actual situation, FIG. 1 is an enlarged plan view of a rectangular twelve-core type ferrule, and in fact there is in some cases a demand for designing a ferrule having a thickness of around 2.0 mm, in which apertures 1 having a diameter of around 0.126 mm are defined at a pitch of around 0.25 mm.
However, in spite of earnest research and development made by outfits concerned in an attempt to manufacture such ferrules by means of plastic moldings according to the design, trial products resulted from the development are poor in heat resistance and high in linear expansion factor, and there are troubles including bending of core pins, so that it is far from achieving dimensional accuracy on the order of microns in terms of the bore diameter and positions of the apertures essentially demanded.
In view of the above-mentioned actual situation in manufacturing premises, the invention is directed to providing a method of manufacturing a multi-core ferrule, manufacture of which has so far been substantially impossible, and which method can relatively easily solve the fundamental subjects including the demanded strict dimensional accuracy and heat resistance.
In order to attain the above-mentioned object, the present invention is comprised of a method of manufacturing a multi-core ferrule, in which method a plurality of flat-surface metal sheets formed with the same plurality of apertures are laminated on one another and fixed together, the improvement wherein the plurality of apertures are designed in positions and diameters such that the plurality of apertures formed in the respective metal sheets having not been laminated and fixed are in communication with one another to be capable of forming cavities.